How to submit an update request?

Question

SQL

Three tables: usersam (idussam, idsam, statyssam,lvl), reis (idsam, idnaprav, dtbegin, dtend, id_reis), polosa (idps, idpolosa, id_user, idsam, idnaprav). How to change the fields in the table polosa and usersam with one query, by condition? If polosa.idsam=0 and if reis.dabegin is greater than dtend, then set the polosa.idsam field to reis.idsam, polosa.idnaprav=reis.idnaprav, usersam.statyssam='On Landing'.

Answer 1

UPDATEupdates one table.

Answer 2

One request - nothing.
It is necessary to write a procedure that will update everything that is needed and where it is needed, and moreover, it will do it in one transaction in order to preserve the integrity of the data.